Massive occurrence of benthic plastic debris at the abyssal seafloor beneath the Kuroshio Extension, the North West Pacific

Ryota Nakajima,Masashi Tsuchiya,Akinori Yabuki,Shuhei Masuda,Tomo Kitahashi,Yuriko Nagano,Tetsuro Ikuta,Noriyuki Isobe,Haruhiko Nakata,Heather Ritchie,Kazumasa Oguri,Satoshi Osafune,Kiichiro Kawamura,Maki Suzukawa,Takuya Yamauchi,Koichi Iijima,Takao Yoshida,Sanae Chiba,Katsunori Fujikura

doi:10.1016/j.marpolbul.2021.112188

Abstract

The abyss (3500–6500 m) covers the bulk of the deep ocean floor yet little is known about the extent of plastic debris on the abyssal seafloor. Using video imagery we undertook a quantitative assessment of the debris present on the abyssal seafloor (5700–5800 m depth) beneath the Kuroshio Extension current system in the Northwest Pacific. This body of water is one of the major transit pathways for the massive amounts of debris that are entering the North Pacific Ocean from Asia. Shallower sites (1400–1500 m depth) were also investigated for comparison. The dominant type of debris was single-use plastics - mainly bags and food packaging. The density of the plastic debris (mean 4561 items/km2) in the abyssal zone was the highest recorded for an abyssal plain suggesting that the deep-sea basin in the Northwest Pacific is a significant reservoir of plastic debris.

Highlights

IntroductionPlastic pollution is an issue emerging as one of the most serious threats to the ocean environment, including the deep-sea ecosystem
This study will allow us to assess the fate of the marine debris leaked from East Asia, which are transported via the Kuroshio current, and determine if they have been accumulating on the deep seafloor off the east coast of Japan
Debris was found at all sites on the seafloor under the Kuroshio Extension (KE) and KE recirculation gyre (KERG) (5700-5800 m depth), some 500 km away from the land (Fig. 2a)

Summary

Introduction

Plastic pollution is an issue emerging as one of the most serious threats to the ocean environment, including the deep-sea ecosystem. This hypothesis has not yet been confirmed experimentally. This study will allow us to assess the fate of the marine debris leaked from East Asia, which are transported via the Kuroshio current, and determine if they have been accumulating on the deep seafloor off the east coast of Japan. This will significantly contribute to our understanding of the fate of ocean plastics

Results

Discussion

Materials and Methods